Electrical insulato bushing



June 6, 1933. J. TURNER ELECTRICAL INSULATOR BUSHING Filed July '7, 1930 am-i Patented June 6, 1933 UNITED STATES PATENT OFFICE JOHN manna, or nonnmwoon, nnenann, assrenoa T mamas: me, or new Yon-x, N. Y.

ELECTRICAL INSULATOL BUSHING Application filed July 7, 1830, Serial No. 486,247, and in Great Britain August 12, 1988.

This invention relates to insulator bushings clude a clamping ring engaging a flat ring for electrical apparatus of all kinds, for exon said outer member. ample oil-immersed transformers, induction The invention also consists in a duplex regulators,condensers, surge absorbers, &c. bushing insulator as set forth above, where- The invention is concerned with bushin s in the flexible connecting member is secured for such apparatus adapted to be complete y rigidly at its ends to said terminals. filled with oil or compound as distinct from The accompanying drawing illustrates bushings containing enclosed air. diagrammatically one convenient construc- The difficulties and drawbacks hitherto met tion in accordance with the present invention. with in apparatus of the kind indicated above In carrying the invention into effect in the u are as follows 4 form illustrated I provide a bushing of double (1) Oil-tight joints especially with ceporcelain sheath construction. mented porcelain parts are extremely difli- The conductor a to be insulated is brought cult to make and maintain. through the centre of the inner (plain rce- (2) In many cases, either due to their size lain sheath b, which latter embo ies a ange or to risk of breakage, the porcelain bush- 0 and is connected to a terminal stem (1 fitted ings must be despatched separate from their to the upper end of the sheath. The upper apparatus. This frequentl necessitates that and lower surfaces of the flan e c are flat and the customers dry out t e apparatus besmooth, e. g. ground thus, an areadaptedto fore installation. be clamped in oil-tight fashion between a ring (3) Porcelain bushings are easily broken g and the surface 0 traversed by the conducin service; such breakage involves loss of oil tor, this surface forming part of a casing r or compound and may allow moisture to enter, containing oil-immersed'electrical apparatus thus necessitating fresh dry out of the appa- (not shown). ratus. The terminal stem d is also clamped against 70 (4) On account of the liability to breakflat surfaces 0, f at the upper end of the age, spare complete bushing insulators must sheath b. be kept in stock by the customer. This form of oil-tight joints with flat porce- The present invention has for its object to lain surfaces is very easy to make and insure 80 overcome all these drawbacks and to provide and simple to maintain. some additional advantages. An outer porcelain shell Z is provided and The invention consists in a duplex bushing this also has flat surfaces enabling its lower insulator for a conductor comprising an inner end to be clamped by a clamping ring n and insulator member carrying a terminal in washer m to the said traversed surface in oilconnection with the conductor, means for tight fashion. outer shell may be fursecuring said member in liquid-tight fashion nished with rain [sheds if desired for Outto the surface traversed by the conductor, an door use. 1 outer concentric easily replaceable insulator The upper end of the outer shell is also furmeniber, means for similarly securing said nis hed with a terminal stem p clamped there- 40 latter member to said surface, a terminal on to, the conductor stem (1 being connected &

said latter member and flexible leads conthereto by flexible leads q. necting together said terminals. The space between the inner and outer por- The invention also consists in a duplex celain is filled with il or compound, leaving bushing insulator as set forth above wherein a small air space f r expansion. The outer 4! said means for securing the outer member inshell being of relatively large diameter is extremely robust mechanically. Breakage of this outer shell by any external force will not affect the inner porcelain so that the apparatus will still remain oil tight. Should 5 the outer shell be broken it can easily and quickly be replaced without involving dismantling or drying out of the apparatus.

The only spare part necessary is the outof shell which involves a small proportion only of the total cost of the bushing.

The apparatus is sent out from the works, completely dried out and with the inner porcelain fitted. N o drying out is required on site, and the customer merely has to fit the outer shell.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A duplex bushing insulator for a conductor comprising an inner insulator member carrying a terminal in connection with the conductor, a flange of insulating material between the ends of said member, means for securing said flange in liquid-tight fashion to the surface traversed by the conductor,

an outer concentric easily replaceable insulator member, a flange of insulating mate rial on the said latter insulator member, means for similarly securing said latter flange to said surface, a terminal on said latter member and flexible leads connecting together said terminals.

2. A duplex bushing insulator as claimed in claim 1, wherein said means for securing the outer member include a clamping ring engaging a flat ring on said outer member.

In testimony whereof I have signed my name to this specification.

JOHN TURNER. 

